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the jerks will slowly disappear, to be followed by a return after a period of rest.

The sympton is most easily elicited and is most commonly present in the upper extremity, though it is occasionly noted in the lower. When testing the leg, the same method is pursued as when examining the arm, the patient being conveniently seated on a table and the leg rapidly flexed and extended at the knee.

It is obvious that this symptom belong to the early period of rigidity in Parkinson’s desease and it is this fact that gives it its value, from diagnostic point of view.

The term « paralysis agitans » is a misnomer ; no patients with this desease have typical paralysis and many of them are without tremor. The essential sign in the desease is the rigidity, and this is frequently an early symptom preceding the tremor, althougt in some cases there may be tremor without rigidity, or at least without sufficient rigidity to admit it may be recognized in a clinical examination. Sofar as I have observed, the sign is not noted in other conditions ; hence when obtained it is strokingly characteristie of >arkinson’s desease.

Its value, from a diagnostic point, is due to its presence in the cases in whitch there is real difficulty in making a diagnostic. The ordinary typieal case of paralysis agitans, with the pillrolling movement, the festination, slooping, and mask-like features, can be recognized at a glance, but there are less developed cases characterized by rigidity and absence of tremor, and frequently in which the desorder is limited to one

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extremity, in which the diagnostic is difficult. It is in this class of cases that I have learned to appreciate the value of this sign. In a number of cases in which. the desorder began in one hand, characterized only by clumsiness and discomfort in the extremity, this sign was elicited and later, after some years, the more frank symptoms of paralysis agitans developed.

As stated above this sign may be absent in cases in which there is a characteristic tremor of Parkinson’s desease, but I have never seen it present in other that Parkinson’s desease ; hence it can be stated that it is a quite positive sign of this condition though its absence by no means conclusively proves that the desorder is not paralysis agitans,